EP1352706A2

EP1352706A2 - Apparatus for processing the circumference of a spectacle lens with a finishing unit for chamfering and grooving

Info

Publication number: EP1352706A2
Application number: EP03007808A
Authority: EP
Inventors: Toyoji c/o Hoya Corporation Wada; Takashi c/o Hoya Corporation Daimaru; Masahiro c/o Hoya Corporation Jinbo
Original assignee: Hoya Corp
Current assignee: Hoya Corp
Priority date: 2002-04-08
Filing date: 2003-04-04
Publication date: 2003-10-15
Anticipated expiration: 2023-04-04
Also published as: ATE347463T1; JP2003300140A; KR100496559B1; EP1352706B1; US20030220056A1; US6908367B2; DE60310153D1; DE60310153T2; CN1229203C; KR20030081023A; EP1352706A3; CN1449881A

Abstract

In an apparatus for processing a lens in accordance with data of the shape of a lens frame, chamfering and grooving of a lens having a small diameter are achieved by a simple mechanism.

An apparatus comprises a holding shaft 41 which is disposed between a main rotating tool 50 and a finishing unit 7 and supports a lens 1 in a manner such that the lens can be freely rotated, a sensor for detecting the position of the lens 145 which detects the rotation angle of the holding shaft 41, a motor 45 for driving the holding shaft 41, a lens unit 4 which freely displaces the lens 1 towards the main rotating tool 50 or the finishing unit 7 based on the rotation angle and data of the shape of the lens frame, and a base unit 2 which displaces the lens unit 4 in the axial direction of the holding shaft 41. The finishing unit 7 is constituted with a rotating tool for chamfering 70 and a rotating tool for grooving 71 which are disposed along the holding shaft 41 at positions separated by a prescribed distance and a driving motor 72 connected to these rotating tools 70 and 71.

Description

The present invention relates to an apparatus for processing a lens which is used for processing the peripheral portion of a lens such as a spectacle lens to provide a prescribed shape so that the lens can be fitted into a lens frame of a spectacle frame.

Prior Art

Heretofore, when a lens such as a spectacle lens is processed so that the lens is fitted into a lens frame of a spectacle frame, the peripheral face of an uncut lens is ground by a grinder or cut by a cutter and the uncut lens is formed into a prescribed shape of the peripheral portion in accordance with data of the shape of the lens frame of the spectacle frame.
Examples of the known processing apparatus for this purpose include, as disclosed in Japanese Patent Application Laid-Open No. 2001-18154, apparatuses in which, after the peripheral portion of a lens is processed by the flat grinding or the beveled grinding using a rotating tool (a grinder) which is freely rotated and grinds the peripheral portion of a lens, chamfering and grooving is conducted as the finishing of the peripheral portion of the lens by using a grinder for chamfering and a grinder for grooving which are coaxially disposed.
In Japanese Patent Application Laid-Open No. 2001-87922, an apparatus for chamfering and grooving the peripheral portion of a lens by a single ball end mill is disclosed.

Object to be solved by the invention

However, as shown in Fig. 15, since conventional apparatuses such as those described above are equipped with a grinder for chamfering the concave face of the lens and a grinder for chamfering the convex face of the lens and these grinders are formed integrally with a grinder for grooving disposed between these grinders for chamfering, it occasionally takes place that, as shown in by the portion A in the Fig., the grinder for grooving protrudes to the outside of the periphery of the grinders for chamfering and the grinder for chamfering protruding at the peripheral portion contacts the lens-holding shaft and interferes with the processing. When this arrangement takes place, in particular, in the case of a lens having a small diameter, the chamfering cannot be conducted. In this example of the conventional apparatus, for changing the chamfering angle, the desired chamfering angle is achieved by inclination of the shaft of the grinder for chamfering. This method has a problems in that, since the chamfering is conducted while the shaft is inclined at an angle varied as desired, the driving mechanism and the supporting mechanism for the tool becomes complicated and the size of the apparatus increases.
In the latter example described above, the grooving is conducted by using the tip of a ball end mill and the chamfering is conducted by using a side face of the same single ball end mill. Since the outer diameter of the ball end mill is decided by the width of the groove formed at the outer peripheral face of the lens, it is necessary that a plurality of processing be conducted at different positions or the processing be conducted while the tool is moved when the area for chamfering is great (or the curvature of chamfering is great). Therefore, problems arise in that the time for the processing increases and the control of the apparatus becomes difficult.
The present invention has been made to overcome the above problems and has an object of providing an apparatus for processing a lens which can achieve chamfering and grooving of a lens having a small diameter using a simple mechanism and can achieve a desired chamfering in a short time.
The present invention provides an apparatus for processing a lens which comprises a finishing unit for chamfering and grooving a peripheral portion of a spectacle lens, the apparatus comprising: a holding shaft supporting the lens, a lens-holding unit which rotates the holding shaft and displaces the lens towards the finishing unit based on data of a shape of a lens frame and a rotation angle of the holding shaft, and positioning means for positioning in an axial direction which displaces the lens in an axial direction of the holding shaft; wherein the finishing unit comprises a rotating tool for chamfering and a rotating tool for grooving which are disposed at positions separated by a prescribed distance along the holding shaft and a single driving means which is connected with the rotating tool for chamfering and the rotating tool for grooving, one of the rotating tool for chamfering and the rotating tool for grooving is selected in accordance with a displacement in the axial direction of the positioning means for positioning in an axial direction, a prescribed position for processing or a prescribed processing amount is set in accordance with the displacement in the axial direction, and the finishing of the peripheral portion of the lens is conducted by using the rotating tool for grooving and the rotating tool for chamfering successively.
The present invention also provides an apparatus for processing a lens which comprises a rotating tool for chamfering used for chamfering a peripheral portion of a spectacle lens, the apparatus comprising: a holding shaft supporting the lens, a lens-holding unit which rotates the holding shaft and displaces the lens towards the finishing unit based on data of a shape of a lens frame and a rotation angle of the holding shaft, and positioning means for positioning in an axial direction which displaces the lens in an axial direction of the holding shaft; wherein the rotating tool for chamfering is constituted with a rotating tool having a hemispherical shape, a chamfering angle or a chamfering amount is set in accordance with a displacement in the axial direction of the positioning means for positioning in an axial direction and a displacement of the lens-holding unit, and the chamfering angle or the chamfering amount can be changed in accordance with the relative position between the rotating tool having the hemispherical shape and the peripheral portion of the lens.
In the present invention, one of the rotating tool for chamfering and the rotating tool for grooving is selected by displacement of the lens-holding unit in the axial direction of the holding shaft and the lens-holding unit and the positioning means for positioning in the axial direction are displaced towards the selected tool based on the data of the shape of the lens frame. Therefore, the prescribed chamfering and the prescribed grooving of the peripheral portion of the lens can be conducted independently. Since the rotating tool for chamfering and the rotating tool for grooving are disposed independently at positions separated by a prescribed distance, interference of the rotating tool for grooving with the lens-holding shaft during the chamfering is prevented and the chamfering and the grooving can be surely achieved even when the lens has a small diameter.
In the present invention, the rotating tool having the hemispherical shape and the lens are relatively displaced in the radial direction and in the axial direction by using the lens-holding unit and the positioning means for positioning in the axial direction and the processing can be conducted at a desired chamfering angle and a desired chamfering amount using a single tool. Therefore, the time for the processing can be decreased while the chamfering is conducted for various shapes.

Brief Description of Drawings

Fig. 1: shows a perspective view of the appearance of the apparatus for processing a lens as an embodiment of the present invention;
Fig. 2: shows a perspective view exhibiting the main portions of the inner construction;
Fig. 3: shows a perspective view exhibiting a base unit, an elevating and lowering unit and a lens unit in the inner construction;
Fig. 4: shows a sectional view of the elevating and lowering unit and the lens unit in the vertical direction when the processing is started;
Fig. 5: shows a sectional view of the elevating and lowering unit and the lens unit in the vertical direction when the processing is completed;
Fig. 6: shows a sectional view of the elevating and lowering unit and the lens unit in the horizontal direction in the condition that the lens is held by the lens-holding shafts;
Fig. 7: shows a sectional view of the elevating and lowering unit and the lens unit in the horizontal direction in the condition that the lens is released from the lens-holding shaft;
Fig. 8: shows a perspective view of the finishing unit at the waiting position (the retired position);
Fig. 9: shows a perspective view of the finishing unit at the processing position (the advanced position);
Fig. 10: shows diagrams exhibiting the grooving, in which (A) shows a perspective view of the finishing unit and (B) shows a sectional view of a lens during the processing;
Fig. 11: shows a sectional view exhibiting the chamfering of the convex face of a lens;
Fig. 12: shows a sectional view exhibiting the chamfering of the concave face of a lens;
Fig. 13: shows a diagram describing the relative positions of the lens and the rotating tool having the hemispherical shape, in which (A) shows the coordinates of the tool and the position of the lens and (B) shows the relation between the apices of the lens and the chamfered portion 1e;
Fig.: 14shows a block diagram exhibiting the control portion; and
Fig. 15: shows a side view exhibiting the relation between a lens-holding shaft and a grinder for finishing in a conventional example.

An embodiment of the present invention will be described in the following with reference to the Figures.
Fig. 1 shows a perspective view exhibiting the appearance of an apparatus for processing a lens 10. Fig. 2 and 3 show perspective views exhibiting the inner construction of the apparatus.
In Fig. 1, at the right side of the front of the apparatus for processing a lens 10 contained in a case having the shape of a rectangular parallel-epiped 11, an operation portion 13 for selecting or inputting the conditions for processing the lens and a display portion 12 for displaying information on the processing such as the data of the shape of the lens frame and the data for the processing are disposed. The operation portion 13 is constituted with touch panels, touch switches, keys or the like. The display portion 12 is constituted with LCD, CRT or the like.
At the front center of the apparatus for processing a lens 10, a door 14 which can be opened or closed as desired and used for inserting or taking out a lens is disposed.
After the entire apparatus is described, the members and the portions will be described in detail.
In Fig. 2, a base unit 2 which is equipped with a main rotating tool 50 (a main means for processing) and can be displaced in the direction parallel to a main shaft 51 (the direction of the X-axis in the Fig.) is disposed at the inside of the case 11. The base unit 2 supports a lens unit (a lens-holding unit) 4 which can be displaced in the vertical direction (in the direction of the Z-axis in the Fig.).
The direction from the right to the left in Fig. 2 (the transverse direction of the apparatus for processing a lens 10) is assigned to the X-axis, the vertical direction (the direction of the height of the apparatus) is assigned to the Z-axis, and the direction from the left to the right in Fig. 4 (the direction towards the inside of the apparatus) is assigned to the Y-axis. It is assumed that these axes orthogonally intersect each other.
In the lens unit 4, a lens-holding shaft 41 which is divided into two portions and selectively holds the center of the lens 1 between the two portions is disposed in a manner such that the lens-holding shaft can be rotated freely. The lens-holding shaft 41 is placed on the vertical line of the main rotating tool (a grinder or a cutter) 50 which is supported by a shaft on a base plate 15. The lens-holding shaft 41 and the main shaft 51 of the main rotating tool 50 are arranged parallel with each other along the X-axis. The lens 1 is held by the lens-holding shaft 41 in a manner such that the face of the lens 1 is placed along a plane perpendicular to the axial line of the lens holding shaft.
A measuring unit 6 comprising styluses 60 and 61 for measuring positions on the concave face and the convex face, respectively, of the lens 1 is fixed on the vertical line of the lens-holding shaft 41.
The styluses 60 and 61 can be displaced in the direction parallel with the lens-holding shaft 41. For the measurement of the position of the lens 1 after being completely processed, the styluses 60 and 61 are brought into contact with both faces of the lens 1 in the condition that the lens unit 4 is elevated and the lens unit 4 is elevated or lowered in accordance with the data of the shape of the lens frame while the lens-holding shaft is rotated.
For processing the lens 1, starting from the condition shown in Fig. 2, the lens unit 4 is lowered after the main rotating tool 50 is rotated and the peripheral portion (the outer peripheral portion) of the lens 1 is ground into the prescribed shape by elevating or lowering the lens unit 4 in accordance with the data of the shape of the lens frame while the lens-holding shaft 41 is rotated.
By elevating or lowering the lens unit 4 based on the data of the shape of the lens frame corresponding to the rotation angle of the lens-holding shaft 41, the grinding to the processing depth in accordance with the rotation angle of the lens 1 is conducted continuously. During the processing, the force of pressing the lens 1 to the main rotating tool 50 (the processing pressure) is provided by the weight of the lens unit 4 itself. The adjustment of the processing pressure in accordance with the material of the lens is conducted by supporting a portion of the weight of the lens unit 4 by a unit for controlling the processing pressure 8 disposed at a position above the lens unit 4.
The position of contact between the lens 1 and the main rotating tool 50 is changed by displacing the base unit 2 in the direction of the X-axis in the Fig. and the selection between the flat grinding and the beveled grinding can be made. The switching between the rough grinding and the finishing grinding can also be made similarly.
A finishing unit 7 (a means for finishing) which comprises a rotating tool for chamfering 70 and a rotating tool for grooving 71 and can be displaced in the direction of the Y-axis (in the inner direction of the apparatus) is disposed at a position above the lens unit 4. When the finishing unit 7 is at the advanced position, the rotating tool for chamfering 70 and the rotating tool for grooving 71 are placed at a position directly above the lens-holding shaft 71. The selection between the rotating tools 70 and 71 is made and the position of the processing is set by elevating the lens unit 4 and driving the base unit 2 in the direction of the X-axis. The finishing is conducted in this condition.
The portions will be described in more detail in the following.
In Fig. 2, 3 and 4, the main shaft 51 in which the rotating tool (a grinder or a cutter having diamond or the like) 50 is disposed and a motor 55 for driving the main shaft 51 are fixed to the base plate 15 at the inside of the case 11. The main shaft unit 5 is constituted with these members as the main components.
The main shaft 51 is, as shown in Fig. 2, supported by a shaft on the base plate 15 along the X-axis in a manner such that the main shaft 51 can be rotated freely and is disposed parallel with the lens-holding shaft 41.
At the end portion of the main shaft 51, a main rotating tool 50 for mechanically processing the lens 1 is attached. The main rotating tool 50 is placed at the central portion in the direction of the X-axis in Fig. 2 and at the front side of the apparatus (at the lower left side in the Fig.). The base end portion of the main shaft (at the right side in the Fig.) is driven by a motor 55 via a belt 57 and pulleys.
In the main rotating tool 50 which mechanically processes the lens 1, as shown in Fig. 2, a rough grinder for flat grinding 50a, a finishing grinder for flat grinding 50b, a rough grinder for beveled grinding 50c and a finishing grinder for beveled grinding 50d are disposed successively from the side of the tip of the main shaft 51 (the left side in the Fig.). The grinding may also be conducted by using cutters as the rotating tool in place of the grinders.
A base unit 2 for driving the lens unit 4 in the direction of the X-axis is disposed at a position inside the main shaft 51 in Fig. 2 (in the direction of the Y-axis, at the right side in the Fig.).
As shown in Fig. 3, the base unit 2 is constituted with a base 20 which can be displaced in the direction of the X-axis and a servomotor 25 (hereinafter, referred to as an X-axis motor) which controls the positioning by driving the base 20 in the direction of the X-axis as the main components.
The base 20 is disposed on guide members 21 and 22 which are fixed on the base plate 15 in the direction of the X-axis in a manner such that the base 20 can be freely displaced. Therefore, the base 20 can be freely displaced in the direction of the X-axis.
In Fig. 3, an inner screw 23 is disposed at a position below the base 20 between the guide members 21 and 22 in a manner such that the inner screw 23 can be rotated freely. An outer screw 24 fixed at the lower face of the base 20 is engaged with the inner screw 23 and the base 20 is driven in the direction of the X-axis by rotation of the screw 23.
One end of the inner screw 23 and the X-axis motor 25 are connected to each other via a gear and a cogged belt 26 and the base 20 is positioned in the direction of the X-axis in accordance with the rotation angle of the X-axis motor 25.
As shown in Fig. 3, four poles 401 to 404 stand on the base 20. Among the four poles, the two poles 401 and 402 penetrate a frame 40 of the lens unit 4 and guide the lens unit 4 in the vertical direction (the direction of the Z-axis) in a manner such that the lens unit 4 can be displaced freely.
As shown in Fig. 3 and 4, the lens unit 4 is driven in the vertical direction and positioned in the vertical direction by the elevating and lowering unit 3 which is displaced in the direction of the Z-axis. The lens unit 4 is positioned in the direction of the X-axis by the base unit 2.
The elevating and lowering unit 3 is, as shown in Fig. 3, 4 and 6, constituted with a screw 31 which is supported by a shaft on the base 20 between the poles 401 and 402 and penetrates the frame 40 of the lens unit 4 in the vertical direction, a positioning member 34 which is engaged with the screw 31 at the inner peripheral portion and can support the lens unit 4 by contacting the frame 40 of the lens unit 4 at the upper end and a servomotor 33 (hereinafter, referred to as a Z-axis motor) which is connected to the lower end of the screw 31 via a cogged belt 32 and a gear, as the main components. The elevating and lowering unit 3 is disposed on the base 20.
In the elevating and lowering unit 3, the screw 31 is rotated by driving the Z-axis motor 33 and the positioning member 34 having an outer screw 35 engaged with the screw 31 is driven in the direction of the Z-axis. The outer screw 35 is displaced in the direction of the Z-axis since the rotating movement in the circumferential direction is restricted by a mechanism at the lens unit 4 as shown later.
As shown in Fig. 4, the positioning member 34 contacts the inner periphery of a hole portion 40A formed in the frame 40 of the lens unit 4 in the vertical direction in a manner such that the positioning member 34 can slide and make a relative displacement in the vertical direction.
At the upper end of the hole portion 40A, a ceiling portion 400 connected to the frame 40 is disposed. As shown in Figs. 3 and 6, at the side of the outer screw 35 of the positioning member 34, a stopper 36 standing in the direction of the Z-axis is disposed at a position such that the stopper 36 can contact the lower face of the ceiling portion 400.
In Fig. 3, the stopper 36 protruding from the upper portion of the positioning member 34 contacts the lower face of the ceiling portion 400 and the weight of the lens unit 4 applied by the ceiling portion 400 is supported by the positioning member 34 comprising the stopper 36 and the outer screw 35. The outer screw 35 and the stopper 36 are connected to each other at each base portion through a base 340.
As shown in Fig. 6, the hole portion 40A of the frame 40 has a sectional shape such that the positioning member 34 and the stopper 36 are stopped by each other around the Z-axis (in the direction perpendicular to the plane of Fig. 6) and the idle rotation of the outer screw 35 by the rotation of the screw 31 is prevented. In other words, the stopper 36 fixed at the side of the outer screw 35 is arrested by the hole portion 40A and the rotation of the positioning member 34 is prevented. Thus, the outer screw 35 is elevated or lowered by the rotation of the screw 31 and the positioning member 34 is displaced in the direction of the Z-axis due to this movement.
When the stopper 36 does not contact the ceiling portion 400, as shown in Fig. 5, the lens 1 supported by the lens unit 4 is brought into contact with the main rotating tool 50 and the weight of the lens unit 4 itself is applied as the processing pressure. The upper end face 34A of the positioning member 34 and the lower face of the ceiling portion 400 do not contact each other and a prescribed gap is formed.
At a position below the ceiling portion 400 faced to the gap, a hole portion 421, where one end of a sensor arm 300 (the means for amplifying a relative displacement) for detecting completion of the processing on the lens unit (in the vertical direction) is inserted, is disposed along the Y-axis in the Fig. in a manner such that the hole portion 421 penetrates the frame 40 across the hole portion 40A.
The sensor arm is, as shown in Fig. 4 and 5, an integrally formed arm having the shape of an inverse L which is composed of an arm 301 extending to the left side in the Figs. (in the direction of the Y-axis) and inserted into the hole portion 421 and an arm 302 extending in the lower direction in the Fig. (in the direction of the Z-axis, to the side of the base 20). The arm 301 and the arm 302 are disposed approximately perpendicularly to each other.
The length of the arm 302 in the vertical direction is set longer than that of the arm 301 in the horizontal direction.
A bending portion 303 at the middle of the sensor arm 300 having the shape of an inverse L is supported by a shaft 420 disposed at the ceiling portion 400 of the lens unit 4 in a manner such that the bending portion 303 can freely swing around the shaft 420 and, therefore, the sensor arm can swing around the X-axis.
Between the arm 302 extending in the direction of the Z-axis and the ceiling portion 400, a spring 310 which pushes the arm 301 extending in the direction of the Y-axis in the lower direction in Fig. 4 and 5 (in the counter-clockwise direction in the Figures) is disposed.
Since the arm 301 inserted into the hole portion 421 crosses the hole portion 40A in the direction of the Y-axis, a penetrating portion through which the screw 31 is inserted is formed and the lower face of the arm 301 faced to the inner periphery of the hole portion 40A can be brought into contact with or separated from the upper end face 34A of the positioning member 34.
Since the sensor arm 300 is pushed in the counter-clockwise direction in the Figures by the spring 310, as shown in Fig. 4, the tip 301A of the arm 301 is brought into contact with the lower side of the hole portion 421 and stopped there in the condition that the upper end face 34A of the positioning member 34 and the arm 301 are separated from each other (in the condition that the stopper 36 is separated from the ceiling 400).
On the other hand, as shown in Fig. 5, in the condition that the stopper 36 of the positioning member 34 contacts the ceiling portion 400 of the lens unit 4 (in the condition that the stopper 36 contacts the ceiling portion 400 as shown in Fig. 3), in other words, in the condition that the positioning member 34 supports the lens unit 4, the upper end face 34A of the positioning member 34 pushes the arm 301 in the upper direction. In this condition, the sensor arm 300 rotates and the arm 302 extending in the direction of the Z-axis is placed at the prescribed position (for example, a position in the vertical direction as shown in Fig. 5).
A bracket 422 protruding along the lower portion of the sensor arm 300 (the arm 302) is disposed at the frame 40. At the prescribed position of the bracket 422 which can be faced to the lower end of the arm 302 swinging around the X-axis, a sensor for detecting completion of the processing (a means for detection) which detects the free end portion of the arm 302 swinging around the X-axis is disposed. The free end portion means the end portion of the sensor arm 300 which is detected by the sensor for detecting completion of the processing 320 and, in the present embodiment, is the end portion of the arm 302.
The sensor for detecting completion of the processing 320 is, for example, constituted with a photosensor such as a photointerruptor. As shown in Fig. 5, when the swinging arm 302 comes to the prescribed position (the position in the vertical direction where the lens unit 4 and the positioning member 34 are brought into contact with each other) and the light of the photointerruptor of the sensor for detecting completion of the processing is interrupted, the sensor is switched at ON and it is detected that the processing has been completed.
The elevating and lowering unit 3 supports the lens unit 4 in the elevating direction. After the lens unit 4 starts the processing of the lens 1, the processing depth (the processing amount) is decided in accordance with the position of the elevating and lowering unit 3 in the direction of the Z-axis. When the prescribed processing depth is achieved, the sensor for detecting completion of the processing 320 is switched at ON. The proceeding of the processing can be detected at every rotation angle of the lens 1 in this manner and, when the output of the sensor for detecting completion of the processing at the entire peripheral portion of the lens 1 shows ON, it is decided that the processing has been completed on the entire peripheral portion of the lens 1.
The lens unit 4 which is displaced by the elevating and lowering unit 3 in the direction of the Z-axis is, as shown in Fig. 3, guided by the two poles 401 and 402 standing on the base 20 in the vertical direction (in the direction of the Z-axis) in a manner such that the lens unit can be freely displaced and is constituted with the lens-holding shaft 41 which is divided into two portions, a motor for driving the lens 45 which rotates the lens-holding shaft 41 and a motor for the lens chuck 46 which changes the pressure of the lens-holding shaft 41 to hold the lens 1, as the main components.
As shown in Fig. 4, the lens-holding shaft 41 which holds and rotates the lens 1 is placed at a position directly above the main rotating tool 50. The direction connecting the axial line of the lens-holding shaft 41 and the axial line of the main shaft 51 is in the vertical direction.
To the frame 40 of the lens unit 4, as shown in Fig. 3 and 6, arms 410 and 411 protruding in the direction of the front of the apparatus (to the lower left side of Fig. 3) are disposed and the frame 40 and the arms 410 and 411 form a rectangle having three sides and open to one side. The arms 410 and 411 support the lens-holding shaft 41.
In Fig. 3 and 6, the lens-holding shaft 41 is divided into two portions at the center, i.e., a shaft 41R supported by the arm 410 and a shaft 41L supported by the arm 411. The arm 41L is supported by the arm 411 at the left side in Fig. 6 in a manner such that the arm 41L is freely rotated. The arm 41R is supported by the arm 410 at the right side in Fig. 6 in a manner such that the arm 41L is freely rotated and can be displaced in the axial direction (in the direction of the X-axis).
The shafts 41L and 41R are rotated by the motor 45 for driving the lens via cogged belts 47, 48 and 49. The cogged belts 47 and 48 are connected to each other through a shaft 430 and the rotation angles of the shafts 41L and 41R are synchronized.
For this purpose, a gear 432 engaged with the cogged belt 47 is fixed to the shaft 41L and a gear 431 engaged with the cogged belt 48 is fixed to the shaft 41R. So that the shaft 41R can be displaced relative to the arm 410 in the direction of the X-axis, the shaft 41R is arrested in the direction of rotation by the key 433 disposed between the shaft 41R and the inner periphery of the gear 431 and, on the other hand, can be relatively displaced in the direction of the X-axis.
In Fig. 6, a chuck mechanism driven by a motor for the lens chuck 46 is disposed at the end portion (at the right side in the Fig.) of the shaft 41R.
In the chuck mechanism, as shown in Fig. 7, an outer screw 442 is formed at the inner periphery of a gear 441 engaged with the cogged belt 440. The outer screw 442 is engaged with an inner screw portion 443 formed at a driving member 461 which can be brought into contact with the shaft 41R in the axial direction.
The position of rotation of the shaft 41R is decided by the motor for driving the lens 45 connected to the cogged belt 48. As for the position of the shaft 41R in the axial direction, as will be described later, the gear 441 is rotated by the rotation of the motor for the lens chuck 46 and the inner screw portion 443 of the driving member 461 engaged with the outer screw 442 is displaced in the axial direction. Due to this displacement, the shaft 41R is pushed in the direction of the X-axis by the driving member 461 and the end portion of the shaft 41R is brought into contact with the lens 1. The pressure of holding the lens by the shaft 41R and the shaft 41L (the holding pressure) can be set at a desired value by the motor for the lens chuck 46. In the present embodiment, the holding pressure for the lens 1 is set by the value of the electric current driving the motor for the lens chuck 46.
In Fig. 7, a receiver of the lens holder 141 is fixed at the tip of the left shaft 41L of the lens-holding shaft 41. To the receiver of the lens holder, a lens holder 16 to which the lens 1 has been fixed in advance is attached. The lens holder 16 can be attached or released freely.
On the other hand, the shaft 41R disposed on the same axial line with that of the shaft 41L moves in the direction of the X-axis and holds the lens at the tip. In other words, the shaft 41R moves towards the lens 1 by being driven by the motor for the lens chuck 46 and presses the lens 1 with a lens presser 142 disposed at the tip. The lens 1 is pressed towards the lens-holding shaft 41L and held between the two shafts. The lens presser 142 is made of a resin having elasticity such as rubber.
At the end face of the lens holder 16 which is formed into a concave shape, the convex face 1a of the lens 1 is coaxially adhered via a double faced adhesive pad 161 and the lens presser 142 presses the concave face 1b of the lens 1. The lens presser 142 is attached to the tip of the shaft 41R holding the lens in a manner such that the lens presser can be swung in any desired direction and the concave face 1b of the lens 1 is pressed with excellent balance without local concentration of the pressure.
As shown in Fig. 7, starting from the condition in which the lens holder 16 having the lens 1 fixed thereto is attached to the shaft 41L, the lens 1 is held by the lens presser 142 in the following manner: the motor for the lens chuck 46 is driven in the prescribed direction (the positive rotation); the gear 441 is rotated in the positive direction due to this movement; and the shaft 41R is displaced to the left side in Fig. 9 by the relative rotation of the outer screw 442 at the inner periphery of the gear 441 and the inner screw portion 443 of the shaft 41R. In the driving member 461 having the inner screw 443, a sensor rod 435 placed parallel with the shaft 41R from a plate 337 disposed at the end portion and protruding to the side of the shaft 41L prevents rotation of the inner screw 443 since the sensor rod 435 is arrested in the direction of rotation by the arm 410 and the driving member 461 is driven in the axial direction alone.
By the displacement of the shaft 41R in the direction of the left side, the driving member 461 pushes the shaft 41R, which is thereby displaced in the direction of the X-axis alone and presses the lens presser 142 to the concave face 1b of the lens 1.
When the motor for the lens chuck 46 is further rotated, the force for pressing the lens 1 increases and the electric current consumed by the motor for the lens chuck 46 increases. The pressure of holding the lens 1 is set at a desired value by detecting the electric current.
On the other hand, when the processing is completed, the motor for the lens chuck 46 is rotated in the reverse direction and the shaft 41R is driven to the right side in Fig. 6. The lens presser 142 is separated from the lens 1 and a prescribed gap is formed between the lens 1 and the lens presser 142 as shown in Fig. 7. The shaft 41R is displaced to the waiting position which allows attachment and detachment of the lens 1 and the lens holder 16. When the driving member 461 is displaced in the direction of the right side in the Fig. by a snap ring (not shown in the Fig.) or the like disposed at a shaft portion having a small diameter 470 which protrudes from the tip of the shaft 41R to the right side in the Fig., the shaft portion 470 is pulled by the driving member 461 and displaced to the right side.
Since the shaft 41R of the lens-holding shaft 41 is displaced in the direction of the X-axis, it is necessary that the position of the shaft 41R be found. When the shaft 41R moves towards the lens 1, it is detected by a sensor not shown in the Fig. that the lens-holding shaft 41 contacts the lens 1 and the pressure of holding the lens 1 is found by monitoring the electric current of the motor for the lens chuck 46. When the shaft 41R moves to the left side towards the waiting position shown in Fig. 7, the prescribed waiting position is detected by a limit switch 435 disposed at the arm 410 of the lens unit 4.
In Fig. 7, the limit switch 435 is fixed to the arm 410 at the position supporting the gear 441.
At the right end portion of the shaft 41R which is the portion of the lend-holding shaft 41 pressing the lens, a sensor rod 435 is disposed via a plate 437 parallel with the shaft 41R and protrudes to the side of the shaft 41L. At the end portion of the sensor rod 435, a detecting portion 437a which can contact the limit switch 435 at the prescribed waiting position is formed.
When the shaft 41R moves to the right side in the Fig., the sensor rod 435 fixed to the shaft 41R also moves to the right side. As shown in Fig. 7, the position where the detecting portion 437a contacts the limit switch 435 is the waiting position of the shaft 41R and the limit switch 435 is switched at ON at this position.
Then, to decide the processing depth in accordance with the rotation angle of the lens 1, the shaft 41L penetrates the arm 411 and a slit plate 143 is fixed at the end portion protruding from the arm 411. By detecting the position of rotation of the slit plate 143 by a photosensor 145 (a lens position sensor) fixed to the arm 411, the position (the rotation angle) of the lens 1 held by the lens-holding shaft 41L is detected.
In the lens unit 4 having the construction described above, when the lens 1 is fixed at the receiver of the lens holder 141, the motor for the lens chuck 46 is driven and the lens-holding shaft 41R is moved to the left side of Fig. 7. The lens 1 is fixed by pressing the lens 1 by the lens presser 142 under the pressure.
As shown in Fig. 3, the main rotating tool 50 is fixed to the base plate 15 and is not displaced. The lens 1 supported by the lens unit 4 is displaced in the vertical direction relative to the main rotating tool 50 by the displacement of the elevating and lowering unit 3 in the direction of the Z-axis and the processing can be conducted to the desired depth.
The position of the lens 1 for the processing can be changed by changing the rotation angle of the motor for driving the lens 46 and the peripheral portion of the lens can be processed to the desired processing depth.
The tool used for the processing can be changed by changing the position of contact between the lens 1 and the main rotating tool 50 by the displacement of the base 20 in the direction of the X-axis.
In Fig. 2, the finishing unit 7 which can be displaced in the direction of the Y-axis (in the direction of the inner side of the apparatus) is disposed at a position above the lens-holding shaft 41 (the right side in Fig. 2).
The finishing unit 7 is, as shown in Fig. 2 and 8, constituted with a base 74 which can be displaced in the direction of the Y-axis, a rotating tool 70 for chamfering the peripheral portion of the lens 1, a rotating tool 71 for grooving the outer peripheral face of the lens 1, a motor for finishing 72 which drives these rotating tools 70 and 71 and a motor for driving the finishing unit 73 which drives the base 74 in the direction of the Y-axis. These components are disposed at positions above the frame (not shown in the Fig.) which stands on the base plate 15.
The rotating tools 70 and 71 stand in the direction of the Z-axis, are disposed at positions separated by the prescribed distance in the direction of the X-axis along the lens-holding shaft 41 and are each supported by a shaft on the base 74.
In Fig. 8, a pair of guide shafts 701 and 702 are fixed to the frame not shown in the Fig. at positions separated by the prescribed distance in the directions of the Y-axis in a manner such that the shafts 701 and 702 are parallel with each other. The guide shafts 701 and 702 pass through holes penetrating stopping members 74a and 74b, respectively, which are disposed at the right side and the left side of the base 74 and the right side and the left side of the base 74 are supported in a manner such that the base 74 can be displaced in the direction of the Y-axis.
At the right side of Fig. 8, a screw 75 is supported by a shaft parallel with the guide shaft 701 at the frame placed on the base plate 15. The screw 75 is driven by the motor for driving the finishing unit 73 via a belt 76.
To the stopping member 74a which is penetrated by the guide 701, a driving member 77 which is engaged with the screw 75 at an outer screw formed at the inner periphery is fixed. The base 74 is driven in the direction of the Y-axis when the driving member 77 is displaced in the direction of the Y-axis in accordance with the rotation of the screw 75.
The rotating tool 70 for chamfering the lens 1 is constituted with a grinder (or a cutter) having the hemispherical shape having a radius R. The rotating tool for chamfering 71 is, as shown in Fig. 8, fixed at a lower end of a shaft 703 disposed in the vertical direction. The shaft 703 is supported by a bearing 704 disposed on the base 74. At the upper end of the shaft 703, a pulley 705 is fixed. The pulley 705 is connected to a pulley 720 of the motor for finishing 72 through a belt 706 (transmission means) and rotated.
The rotating tool 71 for grooving the lens 1 is constituted with an end mill having a narrowed tip. This rotating tool 71 is, as shown in Fig. 8, fixed at the lower end of a shaft 713 disposed in the vertical direction. The shaft 713 is supported by a bearing 714 disposed on the base 74. At the upper end of the shaft 713, a pulley 715 is fixed. The pulley 715 is connected to a pulley 720 of the motor for finishing 72 through a belt 716 (transmission means) and rotated.
These rotating tools may be placed in a manner such that the distance in the direction of the Z-axis from the base 74 to the tip of each tool is set at the same value. Alternatively, these rotating tools may be placed in a manner such that the distance in the direction of the Z-axis from the base 74 to the tip of the rotating tool for grooving 71 may be set shorter than the distance from the base 74 to the tip of the rotating tool for chamfering so that the rotating tool for grooving 71 does not interfere with the lens-holding shaft 41 or the receiver of the lens holder 141 during the chamfering. In other words, the distance from the main shaft 51 to the tip of the rotating tool for grooving 71 may be set at the same value with or longer than the distance from the main shaft 51 to the tip of the rotating tool for chamfering 70.
Since two belts are wound around the pulley 720 of the motor for finishing 72, the belts 706 and 716 are disposed at offset positions in the direction of the Z-axis. In Fig. 8, a belt 716 for driving the end mill is wound at an upper position of the pulley 720. The belt 706 for driving the rotating tool 70 having the spherical shape is wound at a lower position of the pulley 720. The two rotating tools 70 and 71 are driven by one motor 72.
In Fig. 2 and 8, the finishing unit 7 is placed at the prescribed waiting position where the processing is not conducted. In this condition, the two rotating tools 70 and 71 are placed at inner positions in the apparatus (at the right side in Fig. 3) relative to the lens 1 and the styluses 60 and 61.
When the finishing (the chamfering or the grooving) is conducted, as shown in Fig. 14, the two rotating tools 70 and 71 are displaced to positions directly above the lens-holding shaft 41 by driving the motor for driving the finishing unit 73.
In this condition, since the measuring unit 6 is at the waiting position, the rotating tools 70 and 71 are advanced to positions between the styluses 60 and 61. The position having the rotating tools 70 and 71 at the positions vertically above the lens-holding shaft 41 is the advanced position (the position for the processing) of the finishing unit 7.
The finishing is conducted while the base 74 is placed at the advanced position shown in Fig. 9. For example, for the grooving, the base unit 2 is displaced in the direction of the X-axis in accordance with the rotation angle of the lens-holding shaft 41 and the position of the lens measured by the measuring unit described above so that the axial line 71c of the rotating tool (the end mill) 71 is faced to the prescribed position of the peripheral portion of the lens 1d.
While the rotating tool 71 is rotated by driving the motor for finishing 72 and the lens 1 is rotated by driving the motor for driving the lens 45, as shown in Fig. 10(A) and 10(B), the lens unit 4 is elevated or lowered in the direction of the Z-axis in accordance with the rotation angle of the lens 1 and the base unit 2 is driven in the direction of the X-axis. A groove having the prescribed depth is formed along the outer peripheral portion of the lens 1d by the rotating tool 71 constituted with the end mill. Since the rotating tool 70 is connected to the motor for finishing via the belt 706, the rotating tool 70 makes idle rotation without conducting the processing.
When the chamfering follows the grooving, after the outer peripheral portion of the lens 1d is displaced in the lower direction from the tip of the rotating tool by the prescribed distance, the base unit 2 is driven in the direction of the X-axis and the lens unit 4 is displaced to the position where the outer peripheral portion of the lens 1d can be face to the rotating tool 70 having the hemispherical shape.
In the chamfering, for chamfering the convex face 1a, the base unit 2 is displaced in the direction of the X-axis so that the convex face 1a and the outer peripheral portion 1d are placed at a prescribed position directly below the side face of the rotating tool 70c having the hemispherical shape. As shown in Fig. 11, the lens unit 4 is elevated based on the rotation angle of the lens-holding shaft 41 and the position of the peripheral portion of the lens 1 measured by the measuring unit 6 described above and the peripheral portion of the lens 1 is brought into contact with the side face of the rotating tool 70 having the hemispherical shape. In the chamfering of the convex face 1a, the axial line of the rotating tool 70 having the hemispherical shape is, as shown in Fig. 11, placed at a position shifted to the side of the convex face 1a from the outer peripheral portion of the lens 1d.
While the lens-holding shaft 41 is rotated by the motor for driving the lens 45, the lens unit 4 is elevated or lowered and the base unit 2 is displaced in the direction of the X-axis based on the rotation angle of the lens-holding shaft 41 and the position of the peripheral portion in accordance with the rotation angle which is measured by the measuring unit 6 described above and the chamfering of the peripheral portion of the convex face 1a of the lens 1 is conducted.
When the chamfering of the peripheral portion of the concave face 1b of the lens 1 is conducted successively, the outer peripheral portion of the lens 1d is displaced in the lower direction from the tip of the rotating tool 71 by the prescribed distance. Then, as shown in Fig. 12, the base unit 2 is displaced in the direction of the X-axis so that the lens unit 4 is displaced to a position such that the axial line 70c of the rotating tool 70 is placed at the right side of the outer peripheral portion of the lens 1d in the Fig. and the side of the rotating tool 70 having the hemispherical shape can be faced to the outer peripheral portion of the lens 1d.
The lens unit 4 is elevated based on the position of the peripheral portion in accordance with the rotation angle of the lens-holding shaft 41 and the rotation angle measured by the measuring unit 6 described above. While the lens-holding shaft is rotated by the motor for driving the lens 45, the lens unit 4 is elevated or lowered and the base unit 2 is displaced in the direction of the X-axis based on the rotation angle of the lens-holding shaft 41 and the position of the peripheral portion in accordance with the rotation angle which is measured by the measuring unit 6 described above, and the chamfering of the peripheral portion of the concave face 1b of the lens 1 is conducted.
When the finishing is completed, the base 74 is driven to the waiting position, the motor for finishing 72 is stopped and the lens unit 4 is moved to the prescribed position for attachment and detachment. The processing is thus completed.
The apparatus for processing a lens 10 is constituted with the various mechanisms (units) described above and further has a control unit 9 for controlling the mechanisms as shown in Fig. 14.
In Fig. 14, the control unit 9 is constituted with a microprocessor (CPU) 90, a means for memory (a memory, a hard disk and the like) 91 and an I/O control portion (an interface) 92 connected to the motors and the sensors as the main components. The control unit 9 reads the data of the shape of the lens frame sent from the apparatus for measuring the shape of the frame 900 placed at the outside. The control unit 9 also reads the data from various sensors and drives the various motors so that the prescribed processing is conducted based on the properties (the material, the hardness and the like) of the lens 1 set by the operation portion 13. As the apparatus for measuring the shape of the frame, an apparatus such as the apparatus disclosed in Japanese Patent Application Laid-Open No. Heisei 6(1994)-47656 can be used.
The control unit 9 comprises a servomotor control portion 93 which positions the lens unit 4 in the directions of the X-axis and the Z-axis by driving the X-axis motor 25 of the base unit 2 and the Z-axis motor 42 of the elevating and lowering unit 3.
The motor 55 for driving the main rotating unit 50 and the motor for finishing 72 which drives the rotating tools 70 and 71 are each connected to the I/O control portion 92 via driving portions 901 and 902, respectively, and the condition of rotation or the speed of rotation is controlled in accordance with the direction from the microprocessor 90.
The motor for the lens chuck 46 which controls the holding pressure applied to the lens 1 by changing the length of the shaft 41R of the lens-holding shaft 41 is connected to the I/O control portion 92 via a driving portion 911 which controls the holding pressure in accordance with the electric current of driving.
The motor 45 for driving the lens is connected to the I/O control portion 92 via a driving portion 912 which controls the rotation angle of the lens-holding shaft 41 (the lens 1). The microprocessor 90 directs the position of processing the lens 1 based on the data of the shape of the lens frame obtained from the apparatus for measuring the shape of the frame 900, detects the rotation angle of the lens 1 by the sensor for detecting the position of the lens 145 and drives the Z-axis motor 42 so that the processing depth in accordance with the rotation angle based on the data of the shape of the lens frame is achieved.
When the prescribed processing depth is achieved, a sensor for detecting completion of processing 320 which will be described later is switch at ON and the actual position of processing is fed back to the microprocessor 90.
The motor for driving the finishing unit 73 which drives the finishing unit 7 in the direction of the Y-axis is connected to the I/O control portion 92 via a driving portion 913 which controls the positioning.
Outputs from linear scales (not shown in the Fig.) connected to the styluses 60 and 61 of the measuring unit 6 are input into the microprocessor 90.
The operation portion 13 disposed at the front of the cover of the apparatus for processing a lens 10 is connected to the I/O control portion 92 and transfers the directions from the operator (the material of the lens 1 and the processing with or without the beveled processing or the grooving) to the microprocessor 90. The microprocessor 90 outputs the response to the directions and the information of the content of the processing to the display portion 12 via the driving portion 921.
By the control portion 9, data for flat grinding and data for beveled grinding which are used for the flat grinding and the beveled grinding, respectively, are created from the data of the shape of the lens frame. Further, data for grooving and data for chamfering are created by calculation based on the positions of the entire peripheral portion (coordinates of apices in the section of the lens at the side of the convex face 1a and at the side of the concave face 1b) of the lens 1 which are measured by the measuring unit 6 based on the data of the shape of the lens frame.
During the processing, the servomotor control portion 93 drives the X-axis motor and the Z-axis motor in accordance with the data for the processing corresponding to the rotation angle of the lens 1 (the lens-holding shaft 41) which is detected by the sensor for detecting the position of the lens 145 and the lens 1 is displaced relative to the rotating tool. The processing is conducted in this manner.
The procedures of the processing by the apparatus for processing a lens 10 will be described in the following.
The lens 1 is set into the lens-holding shaft 41. The data of the shape of the lens frame are read at the apparatus for measuring the shape of the frame at the outside, the direction on the conditions of the processing (the material of the lens 1 and the processing with or without the beveled processing or the grooving) is received from the operation portion 13, and the direction for starting the processing is further received from the operation portion 13. Then, the procedures of the processing are conducted.
When the start of the processing is directed, the pressing shaft 41R of the lens-holding shaft 41 is displaced to the position for holding the lens shown in Fig. 6 by driving the motor for the lens chuck 46 and the holding pressure is set in accordance with the material.
For processing the lens 1, the main rotating tool 50 is rotated by driving the motor 55. The lens unit 4 is lowered by driving the elevating and lowering unit 3 and the base unit 2 is displaced in the direction of the X-axis to the position where the peripheral portion of the lens 1 is faced to the rough grinder for flat grinding 50a of the main rotating tool 50. The processing depth is provided by the elevating and lowering unit 3 while the lens is rotated by the motor for driving the lens 45 and the rough grinding is conducted to the processing depth calculated at every rotation angle of the lens-holding shaft 41.
When the sensor for detecting completion of the processing 320 of the above lens unit 4 gives ON on the entire periphery, it is detected that the grinding has been completed.
When the rough processing is completed, the lens unit 4 is temporarily elevated. The base unit 2 is moved in the direction of the X-axis to the position where the lens 1 is faced to the finishing grinder for flat grinding 50b of the main rotating tool 50 and the grinding is conducted in the same manner as that conducted for the rough grinding. When the sensor for detecting completion of the processing 320 of the above lens unit 4 gives ON on the entire periphery, the processing on the entire peripheral portion of the lens 1 is completed.
When the grooving by the finishing unit 7 is necessary, the grooving is conducted by forming a groove at the outer peripheral portion 1d of the lens 1 by the rotating tool 71 of the end mill as shown in Fig. 10. Then, the chamfering of both faces of the peripheral portion of the lens 1 is conducted by successively bringing the peripheral portions of the lens 1 at the side of the concave face 1a and the convex face 1b into contact with the side of the rotating tool 70 having the hemispherical shape by driving the base unit 2 in the direction of the X-axis.
As described above, since the rotating tool 70 having the hemispherical shape for chamfering and the rotating tool 71 constituted with the end mill for grooving are independently formed and these tools are disposed at positions separated by the prescribed distance along the lens-holding shaft 41, the rotating tool for grooving 71 does not interfere with the lens-holding shaft or the receiver of the lens holder 141 during the chamfering even when the lens 1 has a small diameter and the chamfering and the grooving can be conducted accurately for the lens 1 having any size.
Since the rotating tool for chamfering 70 and the rotating tool for grooving 71 in the finishing are fixed at the base 74 which is displaced in the direction of the Y-axis and the positioning is conducted by the lens unit 4 which is displaced in the vertical direction and in the direction of the main shaft, it is not necessary that the positioning is controlled by the finishing unit and it is just necessary that the positioning in the advancement be accurately made. Therefore, the mechanism of the finishing unit can be simplified and the cost of production can be decreased. Since the two rotating tools 70 and 71 are driven by a single motor 72, the increase in the number of motor can be prevented. Therefore, the increase in the size of the apparatus can be prevented and the cost of production can be decreased.
Since the lens unit 4 which is displaced relative to the fixed rotating tools 70 and 71 can be positioned in the same manner as that for the flat grinding or the beveled grinding in which the lens 1 is displaced relative to the main rotating tool 50, the main processing and the finishing such as the chamfering and the grooving of the peripheral portion of the lens can be conducted by a single mechanism under a single control for positioning. Therefore, complication in the mechanism and the control can be prevented and the cost of production can be decreased.
The rotating tool 70 having the hemispherical shape is formed with a grinder or a cutter having diamond or the like and has the prescribed radius R as shown in Fig. 13(A). As shown in Fig. 13(B), when the lens 1 (the lens-holding shaft) is elevated from the lower position in the Fig., the chamfering angle  at the portion to be chamfered 1e is decided in accordance with the processing depth Lx in the direction of the X-axis (the displacement in the direction of the axis of rotation of the lens 1) and the processing depth Lr in the direction of the Z-axis (the displacement in the radial direction of the lens 1).
The processing depth Lx is the distance in the direction of the X-axis from an apex C to an apex D. The apex C is the intersection of the line of the outer peripheral face 1d and the line of the concave face 1b in the section of the lens 1 before the processing at one rotation angle. The apex D is the intersection of the line of the outer peripheral face 1d and the line of the chamfered face 1e in the section of the lens 1 after the processing at the same rotation angle. The processing depth Lz is the distance in the direction of the Z-axis (in the radial direction of the lens) from the apex C to an apex E. The apex E is the intersection of the line of the concave face 1b and the line of the chamfered face 1e in the section of the lens 1 after the processing. The angle  between the outer peripheral face 1d and the chamfered face 1e can be set as desired in accordance with the ratio of Lx to Lz. The X- and Y-coordinates of the apex C change depending on the rotation angle of lens 1 (= the lens-holding shaft 41). These coordinates are values obtained by the measurement in advance by the styluses 60 and 61 of the measuring unit 6 described above at the side of the convex face 1a and at the side of the concave face 1b.
The chamfered portion 1e has a concave shape as shown in Fig. 13 since the rotating tool 70 having the hemispherical shape having the radium R is used. The angle between the straight line passing through the apices D and E after the processing and the outer peripheral face 1d is used as the chamfering angle .
Therefore, for the control of positioning in accordance with the chamfering angle of the lens 1, as shown in Fig. 13(B), the ratio of the processing depths Lx to Lz is obtained when the chamfering angle  is decided. Then, when either one of the processing depths in the direction of the X-axis or in the direction of the Z-axis (in the radial direction) is decided, the distances Lx and Lz from the apex C before the processing to the apices D and E, respectively, after the processing can be decided. When circles having a radius R which is the same as the radius R of the hemispherical shape of the rotating tool are drawn at the centers placed at these apices D and E, the intersection of these circles gives the X- and Z-coordinates of the center of the sphere 70 cr of the tool as shown in Fig. 13(A).
When the chamfering angle  and the chamfering amount (the processing depth) are set as described above, the relative positions of the lens 1 and the rotating tool having the hemispherical shape 70 in accordance with the desired chamfering angle  and the desired processing depth (the position of the axial line of the lens-holding shaft 41c in the direction of the Z-axis (Δz) and the position of the apex C in the direction of the X-axis (Δx) in Fig. 13(A)) can be obtained by calculating the coordinates (Xr, Zr) of the center of the sphere 70 cr of the rotating tool having the hemispherical shape 70 from the coordinates of the apex C measured before the processing at every rotation angle. When the rotating tool for chamfering 70 is kept being rotated at the prescribed position (on the vertical line of the lens-holding shaft 41) and the lens unit 4 is elevated and lowered and, at the same time, displaced in the direction of the X-axis by the displacement of the base unit 2 while the lens 1 is rotated, the chamfering at the convex side and at the concave side of the lens 1 can be achieved to the desired chamfering angle  and the desired chamfering depth using a simplified mechanism of the rotating tool. Moreover, since chamfering can be conducted in various manners using a single rotating tool having the hemispherical shape 70, exchange of tools is not necessary and the time of processing can be decreases.
In Fig. 13 shown above, the chamfering is conducted at the side of the concave face 1b. For the chamfering at the side of the convex face 1a, the relative distance Δz between the lens-holding shaft 41 and the rotating tool 70 in the direction of the Z-axis and the relative distance Δx between the coordinate of the apex of the lens 1 and the center 70cr of the rotating tool 70 are obtained from the coordinates of the apices, the chamfering angle  and the chamfering depth at every rotation angle based on the data of the position of the peripheral portion of the lens which are set in advance.
Since the radius R of the rotating tool having the hemispherical shape 70 is constituted independently of the rotating tool for grooving 71, the width of the formed groove is not restricted unlike the conventional case in which the chamfering and the grooving are conducted by using a single ball end mill. Therefore, the radius can be set at the most suitable value for the chamfering.
In the above embodiment, the present invention is applied to the apparatus in which the processing of the lens 1 is conducted by displacing the lens-holding shaft 41 in the vertical direction. The present invention can also be applied to an apparatus having an arm which supports a lens-holding arm in a manner such that that the lens-holding arm can be swung in a conventional manner. For example, when an arm and a positioning member deciding the angle of the arm can be set in a manner such that the arm and the positioning member can be brought into contact with or separated from each other, the relative displacement between the arm and the positioning member is detected after being amplified by a sensor arm, and the position of the contact between the arm and the positioning member is detected based on the relative displacement amplified by the sensor arm, the same effect as that described for the above embodiment can be obtained. The present invention can be applied in the same manner to apparatuses in which a lens-holding shaft is displaced in the horizontal direction.
The embodiments disclosed above are exhibited as examples and it should be considered that the present invention is not restricted to the embodiments. The scope and the range of the present invention are shown not by the above descriptions of the embodiments but by the claims. Any variations within and equivalent to the range of the claims are included in the present invention.

List of reference numbers

1:: A lens
2:: A base unit
3:: An elevating and lowering unit
4:: A lens unit
5:: A unit of rotating tools
6:: A measuring unit
7:: A finishing unit
8:: A unit for controlling the processing pressure
10:: An apparatus for processing a lens
11:: A cover
12:: A display portion
13:: An operation portion
14:: A door
34:: A positioning member
41:: A lens-holding shaft
70:: A rotating tool (for chamfering)
71:: A rotating tool (for grooving)
72:: A motor for finishing
74:: A base

Claims

An apparatus for processing a lens which comprises a finishing unit for chamfering and grooving a peripherals portion of a spectacle lens, the apparatus comprising:

a holding shaft supporting the lens and a lens-holding unit which rotates the holding shaft and displaces the lens towards the finishing unit based on data of a shape of a lens frame and a rotation angle of the holding shaft; and

positioning means for positioning in an axial direction which displaces the lens in an axial direction of the holding shaft; wherein

the finishing unit comprises a rotating tool for chamfering and a rotating tool for grooving which are disposed at positions separated by a prescribed distance along the holding shaft and a single driving means which is connected with the rotating tool for chamfering and the rotating tool for grooving, one of the rotating tool for chamfering and the rotating tool for grooving is selected in accordance with a displacement in the axial direction of the positioning means for positioning in an axial direction, and a prescribed position for processing or a prescribed processing amount is set in accordance with the displacement in the axial direction.
An apparatus according to claim 1, wherein the lens-holding unit can be displaced freely in a vertical direction, the finishing unit is disposed at a position vertically above the holding shaft, and the positioning means for positioning in an axial direction positions the lens relative to the rotating tool for chamfering and the rotating tool for grooving of the finishing unit based on a position in the axial direction which is obtained in accordance with a rotating angle measured in advance based on the data of a shape of a lens frame.
An apparatus according to claim 2, wherein a distance from the holding shaft to the rotating tool for grooving is set longer than a distance from the holding shaft to the rotating tool for chamfering.
An apparatus according to claim 3, wherein the rotating tool for chamfering and the rotating tool for grooving are each disposed at a shaft standing in a direction perpendicular to the holding shaft.
An apparatus according to any one of claims 1 to 4, wherein the rotating tool for chamfering is constituted with a rotating tool having a hemispherical shape.
An apparatus according to any one of claims 1 to 5, wherein the finishing unit is displaced between a position for processing where the rotating tool for chamfering and the rotating tool for grooving are faced to the holding shaft and a prescribed waiting position which is separated from the position where the rotating tool for chamfering and the rotating tool for grooving are faced to the holding shaft.
An apparatus for processing a lens which comprises a rotating tool for chamfering used for chamfering a peripheral portion of a spectacle lens, the apparatus comprising:

a holding shaft supporting the lens and a lens-holding unit which rotates the holding shaft and displaces the lens towards the finishing unit based on data of a shape of a lens frame and a rotation angle of the holding shaft; and

positioning means for positioning in an axial direction which displaces the lens in an axial direction of the holding shaft; wherein

the rotating tool for chamfering is constituted with a rotating tool having a hemispherical shape, and a chamfering angle or a chamfering amount is set in accordance with a displacement in the axial direction of the positioning means for positioning in an axial direction and a displacement of the lens-holding unit.
An apparatus according to claim 7, wherein the rotating tool for chamfering is disposed in a direction perpendicular to the holding shaft and fixed at a prescribed position during the processing.
An apparatus according to any one of claims 7 and 8, wherein the rotating tool for chamfering is displaced between a position for processing where the rotating tool for chamfering is faced to the holding shaft and a prescribed waiting position which is separated from the position where the rotating tool for chamfering is faced to the holding shaft.
An apparatus according to any one of claims 1 to 9, wherein the driving means is constituted with a single motor, and the rotating tool for chamfering and the rotating tool for grooving are simultaneously driven by the driving motor and a transmission means which is wound around the driving motor, the rotating tool for chamfering and the rotating tool for grooving.